Bill, your LHS guy is correct but the HC calls for a 55-60cc engine.

There is a Difference between the FG60 (4.6hp, 6.7K rpm on a 22x10 prop) and the DLE55 (5.5hp, 8.5K rpm on a 22x10 prop) and big difference price. But the FG-60 in my opinion would be fine, of course your decision. That radial sound is awesome.

Bill